manpagez: man pages & more
man pg_receivexlog(1)
Home | html | info | man
pg_receivexlog(1)       PostgreSQL 9.6.6 Documentation       pg_receivexlog(1)




NAME

       pg_receivexlog - stream transaction logs from a PostgreSQL server


SYNOPSIS

       pg_receivexlog [option...]


DESCRIPTION

       pg_receivexlog is used to stream the transaction log from a running
       PostgreSQL cluster. The transaction log is streamed using the streaming
       replication protocol, and is written to a local directory of files.
       This directory can be used as the archive location for doing a restore
       using point-in-time recovery (see Section 25.3, "Continuous Archiving
       and Point-in-Time Recovery (PITR)", in the documentation).

       pg_receivexlog streams the transaction log in real time as it's being
       generated on the server, and does not wait for segments to complete
       like archive_command does. For this reason, it is not necessary to set
       archive_timeout when using pg_receivexlog.

       Unlike the WAL receiver of a PostgreSQL standby server, pg_receivexlog
       by default flushes WAL data only when a WAL file is closed. The option
       --synchronous must be specified to flush WAL data in real time.

       The transaction log is streamed over a regular PostgreSQL connection
       and uses the replication protocol. The connection must be made with a
       superuser or a user having REPLICATION permissions (see Section 21.2,
       "Role Attributes", in the documentation), and pg_hba.conf must permit
       the replication connection. The server must also be configured with
       max_wal_senders set high enough to leave at least one session available
       for the stream.

       If the connection is lost, or if it cannot be initially established,
       with a non-fatal error, pg_receivexlog will retry the connection
       indefinitely, and reestablish streaming as soon as possible. To avoid
       this behavior, use the -n parameter.


OPTIONS

       -D directory
       --directory=directory
           Directory to write the output to.

           This parameter is required.

       --if-not-exists
           Do not error out when --create-slot is specified and a slot with
           the specified name already exists.

       -n
       --no-loop
           Don't loop on connection errors. Instead, exit right away with an
           error.

       -s interval
       --status-interval=interval
           Specifies the number of seconds between status packets sent back to
           the server. This allows for easier monitoring of the progress from
           server. A value of zero disables the periodic status updates
           completely, although an update will still be sent when requested by
           the server, to avoid timeout disconnect. The default value is 10
           seconds.

       -S slotname
       --slot=slotname
           Require pg_receivexlog to use an existing replication slot (see
           Section 26.2.6, "Replication Slots", in the documentation). When
           this option is used, pg_receivexlog will report a flush position to
           the server, indicating when each segment has been synchronized to
           disk so that the server can remove that segment if it is not
           otherwise needed.

           When the replication client of pg_receivexlog is configured on the
           server as a synchronous standby, then using a replication slot will
           report the flush position to the server, but only when a WAL file
           is closed. Therefore, that configuration will cause transactions on
           the primary to wait for a long time and effectively not work
           satisfactorily. The option --synchronous (see below) must be
           specified in addition to make this work correctly.

       --synchronous
           Flush the WAL data to disk immediately after it has been received.
           Also send a status packet back to the server immediately after
           flushing, regardless of --status-interval.

           This option should be specified if the replication client of
           pg_receivexlog is configured on the server as a synchronous
           standby, to ensure that timely feedback is sent to the server.

       -v
       --verbose
           Enables verbose mode.

       The following command-line options control the database connection
       parameters.

       -d connstr
       --dbname=connstr
           Specifies parameters used to connect to the server, as a connection
           string. See Section 32.1.1, "Connection Strings", in the
           documentation for more information.

           The option is called --dbname for consistency with other client
           applications, but because pg_receivexlog doesn't connect to any
           particular database in the cluster, database name in the connection
           string will be ignored.

       -h host
       --host=host
           Specifies the host name of the machine on which the server is
           running. If the value begins with a slash, it is used as the
           directory for the Unix domain socket. The default is taken from the
           PGHOST environment variable, if set, else a Unix domain socket
           connection is attempted.

       -p port
       --port=port
           Specifies the TCP port or local Unix domain socket file extension
           on which the server is listening for connections. Defaults to the
           PGPORT environment variable, if set, or a compiled-in default.

       -U username
       --username=username
           User name to connect as.

       -w
       --no-password
           Never issue a password prompt. If the server requires password
           authentication and a password is not available by other means such
           as a .pgpass file, the connection attempt will fail. This option
           can be useful in batch jobs and scripts where no user is present to
           enter a password.

       -W
       --password
           Force pg_receivexlog to prompt for a password before connecting to
           a database.

           This option is never essential, since pg_receivexlog will
           automatically prompt for a password if the server demands password
           authentication. However, pg_receivexlog will waste a connection
           attempt finding out that the server wants a password. In some cases
           it is worth typing -W to avoid the extra connection attempt.

       pg_receivexlog can perform one of the two following actions in order to
       control physical replication slots:

       --create-slot
           Create a new physical replication slot with the name specified in
           --slot, then exit.

       --drop-slot
           Drop the replication slot with the name specified in --slot, then
           exit.

       Other options are also available:

       -V
       --version
           Print the pg_receivexlog version and exit.

       -?
       --help
           Show help about pg_receivexlog command line arguments, and exit.


ENVIRONMENT

       This utility, like most other PostgreSQL utilities, uses the
       environment variables supported by libpq (see Section 32.14,
       "Environment Variables", in the documentation).


NOTES

       When using pg_receivexlog instead of archive_command as the main WAL
       backup method, it is strongly recommended to use replication slots.
       Otherwise, the server is free to recycle or remove transaction log
       files before they are backed up, because it does not have any
       information, either from archive_command or the replication slots,
       about how far the WAL stream has been archived. Note, however, that a
       replication slot will fill up the server's disk space if the receiver
       does not keep up with fetching the WAL data.


EXAMPLES

       To stream the transaction log from the server at mydbserver and store
       it in the local directory /usr/local/pgsql/archive:

           $ pg_receivexlog -h mydbserver -D /usr/local/pgsql/archive


SEE ALSO

       pg_basebackup(1)



PostgreSQL 9.6.6                     2017                    pg_receivexlog(1)

PostgreSQL 9.6.6 - Generated Fri Dec 1 19:30:25 CST 2017
© manpagez.com 2000-2021
Individual documents may contain additional copyright information.